Force Method for Truss

Force method can be used to solve for a statically indeterminate truss. In this example, we use a truss with excessive member for illustration. The selection of redundant member requires care, where the primary structure after removing such member must be stable internally and externally.

After making one member redundant, we establish two analysis cases and a primary structure, which resembles the structure after we remove the redundant reaction from actual structure. The first case applies original loading on primary structure, while the second case applies redundant member force at its connecting nodes.

For each analysis case, we determine truss deformation using virtual work method. Then, we relate both cases using a compatibility equation, which will then help us to determine the redundant reaction force.

The following introduces the solution to statically indeterminate truss using force method. Watch the video above for full details.